On Tuesday 01 May 2007, Dean Hedin wrote: >> And something that would be better done, and with fewer mistakes, with >> a filter program of some sort. If I have to write it, well, my C is a >> little >> rusty but I think I could come up with something that works eventually. > >This is basically what my emcprobe program did in EMC1: > >You told it a region specified as a range in XY, a safe Z, and resolution in >an .ini file >You then put a probe tip on to match what ever profile you wanted to machine >with.
So far I've only made one tip, with a conical shape, at about 95 degrees included angle, and polished to about an .003 radius so as not to mark up the workpiece. I haven't tried to measure the diamond burr, but I figure its probably bigger than that by the time its cut .010" and settled in for what I hope is the rest of the pattern. Much less included angle too. But what I'm looking at doing, the high crown in the middle of a 1.25" run across it might be 1/8", and my engraving traces won't go off the edge as I'll scale it to stay about 1/8" from the edges. I measured the ID of the inner pipe and came up with .1875", but when I cut a pin on the other end of the tip at .188, it fell in and out, so I had to cut expansion slots in the pin with one of those dremel diamond wheels at a feed rate of about .05"/minute, then drive my pocket knife blade in to expand it a few thou and it grips nicely now. The only spring I could find at Ace Hdwe that fit turned out to be pretty strong for this application, taking well over a pound to compress it the width of the cutout window. A hunk of black ty-wrap was slid in to make the adjustable interrupter itself and by carefull adjustment of that & maybe some glue to make sure it stays put, I can probably bring the tip pressure at the off point to the 4-8 ounce range & not damage the workpiece. Then I figure on making a duplicate surface to use as a test cut scrap for the real engraving. The actual target of all this I only have one of, and its now 90 years old, so I'd rather not further damage it till the pattern is worked out. The last jerk that I had put a barrel in it was handed a finish I did 20 years previously and had that un-mistakable 1965 style Colt-Sauer/Weatherby quality mirror finish on it. I told him to blue it not thinking he would blue the whole thing, just the new barrel. I was horrified when I went back to get it and could see he'd taken it all off, and his final polish grit was maybe 180! Scratch patterns running ever which way at random. It still to this day looks like a J. C. Higgens shotgun after a month rattling around in the ranches pickup, in the bed that is. About due for yet another fresh barrel, I'll see what I can do toward getting it ready for the hot salts tanks myself this time. >The utility then ran by directly talking to EMC through NML and scanned the >surface. >It's output was a gcode file that you could then play back into EMC to >machine the surface. > >The utility could handle multiple region definitions. For example you could >scan one area at a fine resolution, >and another area at a course resolution. > >Another tip. I would use modeling clay to build up smooth approaches to the >edge of the model. >I would then probe a square XY region slightly larger than the model. > >I wouldn't bother trying to scan along curves in the XY plane, since >ultimately I would >be machining with a ball mill and would end up with a scalloped surface. >You kind of want the scallops at a regular interval. Makes it easy to final >finish with a file. >This is pretty much how the professional CAM programs do it. Yeah, the test piece will be cut with a 1/4" ball mill as all curves are convex to the ball anyway. >FYI, It took several hours to probe a 4"x5" surface even at .1 grid >resolution. At my machines speed, I figure about a day to probe that floor plate on a .010" grid. At least that won't be putting hours on the spindle drive. :) >Because of this it is important to make sure the probe does'nt bind and the >wires >to the probe are carefuly mounted out of the way, etc.. Haven't gotten that far, the digikey stuff is still on an ox-cart with ups decals on it, someplace between Thief River Falls Minn., and the middle of West Virginia. >I'd like to get this utility working with EMC2. However I can't afford the >risk of upgrading my machine to >EMC2 right now (too many active projects in the pipeline). For me, the "growing pains" have been relatively minor. Old capabilities haven't gone away that I know of. With backlash comp now working even for steppers, its running pretty sweetly here, some cvs HEAD beta of 2.1 IIRC. I really should do a fresh cvs pull though, its been nearly a year now. OTOH, if its a production cash cow, you don't bring her fresh till the production is going down anyway. :) -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The wages of sin are high but you get your money's worth. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
